The present invention relates to a stage utilizing a piezoelectric actuator or ultrasonic motor movable on a two-dimensional plane and electronic equipment and a printer utilizing the stage.
Recently, an X-Y stage having single axis ables overlapped in the vertical direction at a crossing angle of 90.degree. to each other is often used to measure and process two-dimensional objects.
It is common to employ a method in which the rotation of an electromagnetic motor is converted into a linear motion with a feed screw in each of X- and Y-directions or a method in which linear driving is performed with an electromagnetic linear motor in each of the X- and Y-directions (refer to JSPE-57-10, '91-10-1726).
In the case of the method in which motors and feed screws are combined, however, positioning accuracy is reduced by back-lash at the screw portions or thermal expansion of the screw portions. Further, the mechanism becomes complicated and large because the screw portions must be provided such that they cover the entire amount of desired feed.
In the case of an electromagnetic linear motor, positioning accuracy is limited by the relationship between the poles of the permanent magnet and the coil for generating a magnetic field. Specifically, the coil tends to stop in the vicinity of a pole of the permanent magnet and, as a result, it is difficult to stop the X-Y stage at an intended position. Further, the coil or permanent magnet must be provided such that it covers the entire amount of desired feed, which makes the mechanism complicated and large.
The above-described methods also have had a problem in that they are not usable in an environment where magnetization is avoided because components around the stage are magnetized by an electromagnetic force and circuits round the stage are susceptible to electromagnetic noises.
Meanwhile, ultrasonic motors utilizing a piezoelectric effect of a piezoelectric element are attracting attention in the field of micro-motors. Especially, ultrasonic motors utilizing an oscillator which undergoes stretching oscillation and bending oscillation (duel mode oscillator) are used in various applications because they cause a linear motion, a rotary motion and the like at an object with composite oscillation which is a synthesis of the two kinds of oscillation (see Japanese unexamined patent publication No. H7-184382).